QopenglWidget paintgl issue on imx6

I am new to Qt and below is Qt sample code which we are using with QopenglWidget as base class
void updatebuf()
{
update();
}
void paintGL()
{
/// opengl paint calls..
}
Call from update to paintgl is getting delayed when ever some activity happens on display. So i was wondering if it possible to call paintgl directly and use it for drawing opengl display calls to compensate for delay from update to paintGL.